All I want to do with the new truck is to change to xenon lights, change tyres and alloys and straighten the exhaust pipe and I was told I would loose my warranty if I did.

This federal law: the Magnuson-Moss Warranty - does this only protect consumers in the States?

Any advice or comments would be much appreciated.

Hey,
I imported my Denali from US to Dubai. I have installed many aftermarket mods on it, costing me over $20k. Since my car was imported, I have nothing covered and have to pay for every oil change, part or anything done to my truck. Since yours will be purchased from Liberty Motors, everything will be covered for I think 40k Kilometers. If you have aftermarket products such as xenons, tires, and exhaust it will not effect your warranty at all. I think you should get it installed from the dealers to be on the safe side.
My car has been at the dealers the past 3 weeks and will be done sometime next week. The dealership has been installing many mods that I purchased from US. They do almost stock work, and will do a good job on the work.

I would suggest taking your truck to the GMC/CHEVY dealer in Ras al Khor. PM me and I will tell you who to speak to. You could mention my imported denali with many mods, and everyone in the dealership knows it. They will help you a lot.

You are right about the warranty issue but dealer like working on vehices that are under warranty. Thats how they make their money. They will probably give you a hard time at the beginning but if the aftermarket part you installed didn't affect what needs to be fixed they do have to fix it. Foe example if you PW quit working they can't void the warranty because you put an aftermarket exhaust.